Global Wind Shift Accelerated Thaw at End of Last Ice Age, Study Says

U.S. scientists say a global shift in the planet’s wind and ocean currents, caused by melting ice sheets in the northern hemisphere, is likely to have pushed warmer air and seawater south, putting an end worldwide to the last ice age. The trigger that ended the ice age, roughly 20,000 years ago, was the periodic change in the Earth’s orbit that caused more sunlight to hit the northern hemisphere. Scientists from Columbia University’s Lamont-Doherty Earth Observatory said that orbital shift set in motion the melting of ice sheets across much of the northern hemisphere, which then altered the planet’s wind and ocean currents, warming more southerly regions and pulling carbon dioxide from the ocean’s depths into the atmosphere, accelerating the heating of the planet. The Columbia scientists pieced together this sequence of events by analyzing climate data from caves, polar ice cores, and deep-sea sediment. “These same linkages that brought the Earth out of the last ice age are active today, and they will almost certainly play a role in future climate change as well,” said Bob Anderson, a geochemist at Lamont-Doherty and coauthor of the study, published in the journal Science.